October, 1920 



BETTER FRUIT 



Experiments with Pickering Bordeaux Spray 



EFFORTS to obtain a copper fungi- 

 cidal spray for fruits and vege- 

 tables that would be as efficient as 

 but less expensive than standard Bor- 

 deaux mixtures, have led to encour- 

 aging experiments with the Pickering 

 Bordeaux sprays, the results of which 

 are contained in a bulletin now issued 

 by the United States Department of 

 Agriculture. The high price of cop- 

 per sulphate, known as bluestone or 

 blue vitrol, during the war caused 

 chemists of the department to turn 

 their attention to the Pickering Bor- 

 deaux sprays, which contain less of 

 this high-priced chemical. 



The so-called Pickering Bordeaux 

 sprays had been tested to a limited 

 extent in England, where laboratory 

 tests indicated that they were more 

 efficient per unit of copper than the 

 Bordeaux sprays. Pickering sprays, 

 sometimes called Pickering limewater 

 sprays, are prepared by mixing satu- 

 rated limewater with diluted solutions 

 of copper sulphate, and contain their 

 copper in the form of basic copper 

 sulphates. If the results obtained by 

 Pickering, the British chemist, from 

 whom the sprays get their name, in 

 the laboratory in England hold true 

 under field conditions in America, it 

 is abvious that a great saving in cop- 

 per in this country may be effected. 



It is believed that the experiments 

 by the department lay a basis for fur- 

 ther studies to be conducted in various 

 parts of the country. The opinion is 

 expressed that from the information 

 provided in the bulletin the various 

 agricultural experiment stations and 

 other agencies in the country will be 

 able to devise formulas for copper fun- 

 gicidal sprays for certain crops made 

 with less copper sulphate than stand- 

 ard Bordeaux, which will prove just 

 as efficient as the more expensive 

 sprays. It would be impracticable, it 

 is pointed out, for the department to 

 devise these formulas itself. Field 

 conditions vary in different sections 

 of the country, and experiments would 

 have to be conducted in these dif- 

 ferent sections in order to work out 

 a spray suitable to local needs. 



Tests Cover Three Seasons. 



The experiments, which covered 

 three seasons, were conducted with 

 Pickering Bordeaux sprays containing 

 the equivalent of from .06 to .7 per 

 cent of copper sulphate. Their effi- 

 ciency was compared with that of 

 standard Bordeaux mixtures contain- 

 ing the equivalent of from .75 to 1.25 

 per cent of copper sulphate. 



The results of the tests made on 

 potatoes in Maine indicated that, per 

 unit of copper present, the Pickering 

 Bordeaux sprays were twice as effec- 

 tive as the standard Bordeaux mix- 

 ture. The strongest Pickering Bor- 

 deaux sprays, containing the equiva- 

 lent of from .6 to .7 per cent of cop- 

 per sulphate, controlled late blight on 

 potatoes and the fungous rots of can- 

 berries in New Jersey very effectively. 



Their control of certain fungous dis- 

 eases on grapes and apples was not 

 definitely determined, the results be- 

 ing complicated by burning or other 

 injury to the foliage and fruit. Pick- 

 ering sprays containing less than the 

 equivalent of .6 per cent of copper 

 sulphate were not effective as fungi- 

 cides for potatoes and probably not 

 for cranberries. 



Increased yields of tubers were ob- 

 tained on plats of potatoes treated 

 with standard Bordeaux and with the 

 stronger Pickering sprays, indicating 

 that the latter sprays exerted similar 

 stimulating and protective action on 

 the plants. The adhesive properties 

 of Pickering Bordeaux sprays varied 



Page 21 



with the foliage to which they were 

 applied. They adhered to potato and 

 cranberry leaves in practically the 

 same degree as the standard Bordeaux, 

 to apple leaves in a somewhat higher 

 proportion, and to grape leaves in a 

 lower proportion. 



No Harm to Maine Potatoes. 



No injurious effects followed the 

 application of Pickering Bordeaux 

 sprays to potatoes in Maine or to cran- 

 berries in New Jersey. The sprays, 

 however, proved to be too caustic for 

 use on apples in Virginia or on grapes 

 in New Jersey and Virginia. Picker- 

 ing Bordeaux sprays, it is said, can 

 not be used on tender foliage. 



Barium-water sprays of the Picker- 

 ing type, made with barium hydrate 

 instead of lime and containing the 



[ This is one of a series ] 



Rest 



If you were a tree, 



After a big crop and long summer, 



You would want a rest, 



A rest from growth and insects. 



Give your trees an early bath with 



ZENO 



It will kill the various scale, stop their damage, 

 Destroy the eggs of red spider and aphis, 

 Which would later mean millions of insects, and 

 Destruction to the crop— harm to the trees. 



ZENO 



Is an internationally used 



Miscible oil spray, and these are reasons why 



It has proved the best by years of test. 



MANUFACTURED ONLY BY 



Eastbay Chemical Co., Inc. 



of Emeryville, California 



[Zeno may be had of your local Distributor, Fruit Company 

 Exchange, or by writing to us direct] 



SPOHN & WING, Northwest Agents 



223 Sherlock Building, Portland, Oregon 



